Inpatient Hospitalization Costs Associated with Birth Defects Among Persons Aged <65 Years — United States, 2019

Changing treatments and medical costs necessitate updates to hospitalization cost estimates for birth defects. The 2019 National Inpatient Sample was used to estimate the service delivery costs of hospitalizations among patients aged <65 years for whom one or more birth defects were documented as discharge diagnoses. In 2019, the estimated cost of these birth defect-associated hospitalizations in the United States was $22.2 billion. Birth defect-associated hospitalizations bore disproportionately high costs, constituting 4.1% of all hospitalizations among persons aged <65 years and 7.7% of related inpatient medical costs. Updating estimates of hospitalization costs provides information about health care resource use associated with birth defects and the financial impact of birth defects across the life span and illustrates the need to determine the continued health care needs of persons born with birth defects to ensure optimal health for all.


Introduction
In the United States, major structural birth defects attributable to genetic, chromosomal, teratogenic, or unknown etiologies affect approximately 3% of live births (1) and are the leading cause of infant mortality, responsible for 21% of newborn and infant deaths (2). Their treatments incur significant financial costs throughout a person's lifetime. As treatments and medical costs change, updates to hospitalization cost estimates for birth defects are needed.

Methods
Developed for the Healthcare Cost and Utilization Project (HCUP), the National Inpatient Sample (NIS) is the largest publicly available, all-payor inpatient care database in the United States.* NIS uses a 20% systematic sampling of all * https://www.hcup-us.ahrq.gov/db/nation/nis/NISIntroduction2019.pdf discharges from short-term, nonfederal community hospitals. Because NIS does not identify patients across multiple hospital visits, the unit of analysis for this study is individual hospitalization rather than individual patient. To reduce the impact of potential miscoding of age-related abnormalities as birth defects (particularly cardiovascular defects) (3), only patients aged <65 years discharged during January 1-December 31, 2019 were included. Birth hospitalizations were determined separately from other hospitalizations during the first year of life to better differentiate the costs of birth defects from routine delivery costs. Records missing values of age or billed charges were excluded. Sampling weights for the remaining hospitalizations were adjusted to retain total hospitalization frequency and cost.
Cost estimates were calculated as the product of the amount billed for a hospitalization and the corresponding hospital-level cost-to-charge ratios. HCUP-provided cost-to-charge ratios are computed on an annual basis for each hospital (total institutional service delivery costs divided by total amount charged by Birth defects were identified by scanning up to 40 available diagnosis code fields associated with each hospitalization among codes Q00-Q99 (congenital malformations, deformations, and chromosomal abnormalities) of the International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM). Patent ductus arteriosus (Q25.0) and atrial septal defect (Q21.1) were not considered birth defects when occurring in neonates aged <28 days or with an associated indicator of preterm birth (P07.2 or P07.3). In addition, 23 conditions classified within the Q00-Q99 code range that are commonly considered benign or are otherwise unlikely to contribute to hospitalization costs were not considered birth defects for the purposes of this analysis (Supplementary Table, https://stacks.cdc.gov/view/cdc/130207).
Sampling weights were applied to calculate national estimates of hospitalization frequency and cost. Mean, median, and total costs were calculated by patient demographic and birth defect code characteristics. Mean hospitalization costs were stratified by age group for selected individual birth defects and birth defect categories. If a hospitalization was associated with more than one defect included in the  Abbreviations: ICD-10-CM = International Classification of Diseases, Tenth Revision, Clinical Modification; USD = U.S. dollars. * Identified by scanning up to 40 available fields for ICD-10-CM diagnosis codes Q00-Q99: congenital malformations, deformations, and chromosomal abnormalities. Patent ductus arteriosus (Q25.0) and atrial septal defect (Q21.1) were not considered birth defects when occurring in neonates aged <28 days or with an associated indicator of preterm birth (ICD-10-CM codes P07.2 or P07. 3). An additional 23 conditions of lesser clinical importance classified within the Q00-Q99 code range were not considered birth defects. † Birth defects categories correspond to blocks of ICD-10-CM diagnosis codes: cardiovascular (Q20-Q28), central nervous system (Q00-Q07), chromosomal (Q90-Q99), , and other syndrome (Q87). "Other defect" includes birth defects of the face and neck (Q18), respiratory system (Q30-Q34), and other congenital malformations (Q86 and Q89). Critical cardiovascular defects (https://www.cdc.gov/ncbddd/heartdefects/facts.html) were operationalized using the National Birth Defects Prevention Network Congenital Malformations Surveillance Report (https://www.nbdpn.org/docs/Birth_Defects_Data_and_Directory_2022.pdf). The specific defects included are only those defined in the National Birth Defects Prevention Network Congenital Malformations Surveillance Report; birth defects not included contribute to frequencies and costs aggregated by birth defect category and overall. Because a single hospitalization might include more than one specific birth defect, individual birth defect frequencies might sum to >100% of birth defects categories or overall frequencies, and mean costs multiplied by frequencies will correspondingly sum to >100% of total costs.

Discussion
During 2019, the cost of hospitalizations for persons aged <65 years with a birth defect diagnosis code was estimated at $22.2 billion. These hospitalizations were associated with disproportionately high costs, constituting 4.1% of all hospitalizations among persons in the United States aged <65 years and 7.7% of total costs. Nearly one half of hospitalization costs associated with birth defects occurred among neonates and infants, and these costs disproportionately affected persons aged <1 year during nonbirth hospitalizations. Defects of the cardiovascular system were the most prevalent birth defects, were associated with disproportionately high ($9.8 billion) hospitalization costs, and included many of the costliest individual birth defects.

FIGURE. Weighted estimates of median costs of hospitalizations, by birth defect* , † and age group at admission -National Inpatient Sample, United States, 2019
Birth hospitalization <1 yr nonbirth hospitalization 1-5 yrs 6-18 yrs 19-64 yrs Using 2013 NIS data, the total cost of birth defect-associated hospitalizations was estimated to be $22.9 billion for all ages and $19.1 billion for persons aged <65 years (4). Those estimates included adjustments for professional fees, which historically added 20%-25% to facility costs (5). Applying the same adjustments to the current estimates yields a 2019 estimate of $26.6-27.8 billion in total birth defect-associated hospitalization costs for persons aged <65 years. When adjusted to 2019 hospital care prices, the 2013 cost estimate is $21.0 billion for persons aged <65 years.** The share of birth defect-associated expenditures among total hospitalization expenditures was similar among all age groups: 5.2% in 2013 and 5.5% in 2019.

Limitations
The findings in this report are subject to at least five limitations. First, determining which costs are directly attributable to birth defects is challenging because of difficulties in identifying all sequelae of birth defects and their respective codes, the coding of minor birth defects, and the possible miscoding of some acquired structural or functional abnormalities as ** https://meps.ahrq.gov/about_meps/Price_Index.shtml birth defects (3). Excluding hospitalizations for persons aged ≥65 years reduces the risk for miscoding but fails to identify the contribution of birth defects among this age group. Second, the potential for two or more birth defects to be documented during the same hospitalization could lead to overestimation of costs for findings presented by individual defect or category. Third, cost-to-charge ratios calculated at the hospital level do not necessarily accurately reflect the costs of different types of hospital services (6), which could bias estimates of a person's hospitalization costs in an unknown direction. Fourth, HCUP costs are limited to facility fees and fail to include physician or professional fees, thereby underestimating birth defect-associated hospitalization costs. Finally, it is difficult to distinguish the relationship between preterm birth and birth defects, and some of the birth defect-associated costs among preterm infants were possibly due to their prematurity rather than their birth defect.

Implications for Public Health Practice
Updated estimates of hospitalization costs for specific birth defects provide critical information about health care resource use. These data highlight the financial impact across the life

Summary
What is already known about this topic?
Estimates of birth defect-associated hospitalization costs must be updated as detection, diagnosis, and treatment evolve for numerous birth defects.
What is added by this report?
During 2019, among patients aged <65 years, 4.1% of all hospitalizations and 7.7% of related inpatient medical costs were associated with birth defects. The total estimated cost of birth defect-associated hospitalizations was $22.2 billion.
What are the implications for public health practice?
These updated estimates of hospitalization costs illustrate the importance of continually determining the health care needs of persons with birth defects to ensure optimal health for all. span and illustrate the need to understand the continued health care needs of persons born with birth defects to ensure optimal health for all.